Topic: Smart Contract in Bitcoin (Read 4750 times)

XCP ,OMNI,RSK
Three Bitcoin smartcontract,look forward to the new era of btc.

Dryja had a talk on updating this concept at Scaling Bitcoin in Stanford -  https://www.youtube.com/watch?time_continue=7045&v=LDF8bOEqXt4 (other presentations are here: https://scalingbitcoin.org/presentations)

The PDF is here: https://adiabat.github.io/dlc.pdf

Other Links:

https://coinjournal.net/bitcoins-lightning-network-can-used-decentralized-betting-platform/

Notable Quote:

“These things work great with friends, but bitcoin is the currency of enemies” - Thaddeus "Tadge" Dryja

Thanks man

A smart contract does not explicitly have to be based on ethereums blockchain. Neither does it have to be decentralized.
Ethereum is not the only platform which introduced smart contracts on the blockchain. But it is the most accepted and adopted.
Smart contracts (in future) could also be handled by a blockchain which is not completely decentralized. Licences, for example, could be easily
handled via smart contracts on a (non-public) "centralized blockchain".

This smart contract is a piece of code that runs on ethereum's blockchain and as such is by definition decentralized. It is a self executing contracts with the terms of the agreement between buyer and seller being directly into line of code. It does not care about who wrong whom or what your name is.Once it live on ethereum's blockchain, no one can alter it.

yup, here we go! thx so much, fully agree 
This is why I raised this question. The trolls here seem to think, that smart contracts = turing complete machine, is fancy coding language (which removes me from the burden of using my brain), is ETHEREUM transported into Bitcoin, cause flippening will happen (haha, what a laugh!!!), and much more stupid reasons. Those noobs seem to not even know what they are talking about...

I should stop ranting here, and show how to provide s.th. to the community (still hoping that some people come out of there noob zone and start to learn):
 
BITCOIN HAS ALREADY SMART CONTRACTS!
Examples and use cases:

e.g. the link you mentioned (https://github.com/bitcoin/bips/blob/master/bip-0112.mediawiki):

or something like this:
or more precise:
n-of-m multisig is the easiest form of a contract.
escrow service is the next layer (as in examples above).
And then we can create very specific constructs like:
CHECKSEQUENCEVERIFY: lock some Satoshis until a specific number of block have passed, before I can use them, and if I really, really need the coins before, have a 2-3 multisig to release them immedeatly
CHECKLOCKTIMEVERIFY: lock some Satoshis until a specific number of block appears (aka my son is 18 years old...), but use a 2-3 multisig to release the funds in case funds are required earlier
It goes even up to the point where you can create tx spends, where the hash of a condition must be equal to a previously defined value.
I see some limitations when trying to use Oracles (aka data from "outsides"), maybe data from exchanges, or from real live (in case of death). 

Some more example in Andreas' book "Mastering Bitcoin" (second edition) in the chapter "Timelocks".
or here in the forum
https://bitcointalksearch.org/topic/is-this-bip65-sample-script-standard-1300723
https://bitcointalksearch.org/topic/double-check-my-relative-locktime-script-1558207
https://bitcointalksearch.org/topic/how-to-use-opchecksequenceverify-1952248
or here:
https://www.reddit.com/r/Bitcoin/comments/4kit49/is_it_safe_to_use_cltv_for_recurring_payments/
https://www.reddit.com/r/Bitcoin/comments/4p4klg/bitcoin_core_project_the_csv_soft_fork_has/d4i01he/
and here:
https://en.bitcoin.it/wiki/Timelock
https://en.bitcoin.it/wiki/Contracts

And look at the way how exchanges store much of the funds into cold wallets automatically. These are also smart contracts.
Also the scripting language allows up to 10 kilobytes of code (!), to create smart contracts.
SO YES; BITCOIN HAS SMART CONTRACTS!

I haven't seen a single example by noobs, what a smart contract is, but a lot about there limitations ("scripting is dumb, cause usage of brain to learn scripting language is too complicated for me"). All are complaining that things need to get improved, without saying, what does not work in bitcoin. This is reddit niveau. Reddit it is the right forum to complain, without providing any efforts to improve bitcoin. Even better, there you can improve your reputation by posting much of this shit. Go there... ooops, I wanted to stop ranting 

I think I want to say, look at the examples, tell us what you want to do, what you think is missing, and how we can help to implement smart contracts.

Actually this is pretty clear defined: "A smart contract is a computer protocol intended to facilitate, verify, or enforce the negotiation or performance of a contract." - https://en.wikipedia.org/wiki/Smart_contract
Smart contracts in combination with crypto currencies makes it a system where you dont have to trust a person. A contract will be enforced. Decentralized.



Anything could be those use cases. For example some escrow service or a whole signature campaign which pays out per posts could be created.
Anything you can program can be coded into a smart contract.

I am curious about the "old tech" and "new tech", is it possible that Ethereum replace bitcoin in the future?

We will see another coin split if this ever happens.Though i believe ETHS smart contract is one of its kind and that is solving its purpose already.
And i donot think bitcoin also need smart contact feather at all.

I think the value of ethereum will not dip. My point of view is that if bitcoin introduces the smart contracts those security and privacy will improve and it might change the fact that bitcoin will go higher to its prize from now. I think it will not get ethereum to go dip maybe ethereum will go high a little bit too.

I think that extending bitcoin capabilities through hardcoded smart-contracts is one thing and would be great, but attaching even with a sidechain "turing complete" VM is a most horrible idea ever. Look at the Ethereum with 10x more security and scalability issues.

If that happens, the ETH will no longer be valid
But it costs too much network resources and it will make the miners disagree

Smart contract is the reason why Ethereum is the main challenger to Bitcoin.

A Bitcoin ERC20 like + smart contract would kill Ethereum.

Howewer, Bitcoin is mainly used as a store value while Ethereum is a platform used for creating Dapp

I think Smart contract could be a  very important and necessary feature for Bitcoin. It is like a Mobile app doing some automated and very Basic  stuff like waking you up at 7am, answer phone calls when you're unavailable or sending emails/text messages at a specified time.
There are times I get seriously limited using Bitcoin and all I can think of is moving to Cryptocurrencies with smart contracts.

Question is how easy can Smart Contract be implemented  Bitcoin. If it were that easy I guess developers would have implemented it long ago?

Yeah its possible to do anything with a hard fork. You could hard fork and add any feature. The problem is getting enough of the network onboard to make the network secure. So it has to be cost effective with hashing power. Cause a fork of bitcoin not only needs to compete with bitcoin but existing solutions like Ethereum.

Would it be possible to implement another hard fork in the bitcoin blockchain and introduce the smart contract logic instead of doing it on a side chain like RSK?

I don't think this is a route Bitcoin will take. There are many good examples of Coins for Smart Contract technology and Bitcoin sees itself as a pure Currency. Don't think this will happen.

Where can i find something like whitepaper for smart contracts on bitcoin? Do bitcoin realy need smart contracts? With confirmation of 10 minutes and litle size of blocks it will be slow and it will rise fees if i understand it right.  Also it is many work to do for developers to implement contracts, and at the same time they have many issues to figure out. Maybe it is better for bitcoin to stay as currency.

I think a lot of the people posting here don't know that bitcoin already has contracts. Multisig, timelocked coins, payment channels, trustless escrow etc all exist right now as smart contracts with their code on the bitcoin blockchain. Maybe this thread is instead thinking that we should make bitcoin smart contracts more like ethereum smart contracts.

Would that be a good idea? What are some cool things that ethereum smart contracts can do that we can't already do on bitcoin?

What about colored coins? We've been issuing tokens that way since I think before ethereum even existed. Not that I don't like what ether is doing (I do have a little) but I don't think that I see the appeal that everyone else seems to see.

I guess part of the problem is that everyone expects smart contracts to be these hyper-complex decentralized applications while in reality most decentralized applications either a) don't require a turing complete scripting language or b) don't require a blockchain.

The type of smart contracts that will see actual long-term usage will be simple ones like you described. Alas op_codes are hard and it's easier to sell tokens for the decentralized Uber of X.